Actually it explains why everyone has innate racial profiling, even members of the target group. It's also why, even if a policy against it is adopted, it is immensely hard to actually change.
It's also the case that violence is so unlikely at any given encounter that it isn't rational to worry about it (in the US, there are billions of stranger-stranger encounters in a given year, millions of incidents of violence).
I guess someone might argue that arranging for encounters that are 99.9% likely to be violence free compared to encounters that are 99.8% likely to be violence free is worthwhile, but their glances probably aren't powerful enough to actually create that difference.
http://www.bjs.gov/content/pub/ascii/vvcs9310.txt
It's also the case that violence is so unlikely at any given encounter that it isn't rational to worry about it (in the US, there are billions of stranger-stranger encounters in a given year, millions of incidents of violence).
I guess someone might argue that arranging for encounters that are 99.9% likely to be violence free compared to encounters that are 99.8% likely to be violence free is worthwhile, but their glances probably aren't powerful enough to actually create that difference.